Guidance Note QGN 11
Handling Explosives
in Underground Mines
Explosives Act 1999 Mining and Quarrying Safety and Health Act 1999
Coal Mining Safety and Health Act 1999
October 2008, Version 3
GUIDANCE NOTE – QGN11
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Handling Explosives In Underground Mines
This Guidance Note has been issued by Safety and Health of the Department of Natural Resources and Mines.
This Guidance Note is not a Guideline as defined in the Mining and Quarrying Safety and Health Act 1999 and the Coal Mining Safety and Health Act 1999. In some circumstances, compliance with this Guidance Note may not be sufficient to ensure compliance with the requirements in the legislation.
Guidance Notes may be updated from time to time. To ensure you have the latest version, either check the Department of Mines and Energy website or contact your local inspector of mines.
North Region PO Box 1752 Townsville Qld 4810 (07) 4760 7404 Fax (07) 4760 7400
North Region PO Box 334 Mount Isa Qld 4825 (07) 4747 2158 Fax (07) 4743 7165
North Region PO Box 210 Atherton Qld 4883 (07) 4095 7023 Fax (07) 4091 2844
Central Region PO Box 1801 Mackay Qld 4740 (07) 4953 0860 Fax (07) 4953 2761
Central Region PO Box 548 Rockhampton Qld 4700 (07) 4938 4187 Fax (07) 4938 4331
South Region PO Box 1475 Coorparoo Qld 4151 (07) 3238 3722 Fax (07) 3405 5346
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FOREWORD
QGN11 - HANDLING EXPLOSIVES IN UNDERGROUND MINES
The Queensland mining and quarrying industries are Australia’s largest users of commercial
explosives at approximately 500 000 tonnes each year. Explosives have been the primary
method of breaking and loosening rocks since the introduction of black powder. Today’s
wide range of commercial explosives are safer to use but still represent a major hazard due
to the enormous amount of energy that can be rapidly converted into gases at high
temperature and pressure.
This document, Guidance Note for Handling of Explosives in Underground Mines, covers an
important aspect of safety and health in the mining industries. We have entered a new era
with heightened international terrorist activity necessitating changes to our approach to
explosive use. This component of our industry has been subject to extensive change to
ensure appropriate standards exist for the safe handling and use of explosives. We have
seen crucial changes to explosives in the way of increased security requirements for
storage, transport and use.
These changes have been implemented to restrict explosives and explosives activities in the
community to those authorised by the Chief Inspector of Explosives and of acceptable
safety. Furthermore, it provides best practices as well as management and control of
hazards associated with explosives. Many of these innovations bring advantages to the
operator and worker alike, in the way of improved operating procedures and blast results.
This document was prepared to assist mines and quarries in identifying the hazards and
implementing the necessary controls to ensure the safety and health of all persons involved
in the processes of storage, use and transport of explosives, and provide information on the
methods available to achieve an acceptable level of risk. Mines in Queensland should use
this Guidance Note in conjunction with the relevant legislation dealing with explosives:
Mining and Quarrying Safety and Health Act 1999 or
Coal Mining Safety and Health Act 1999, and the
Explosives Act 1999
Peter Minahan Bob Sheridan
Chief Inspector of Mines Chief Inspector of Explosives
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1 PURPOSE AND SCOPE
This Guidance Note QGN11 is provided to assist competent persons in the safe and
secure storage, use and transport of explosives by within the Queensland
underground mining industry. The note provides information to be considered during
the risk management process to assist in determining acceptable underground
blasting practices. The information contained within is not merely limited to use in
conducting job safety analyses but can be used when implementing safe operating
procedures and safety and health management systems. The risk management
process should be conducted with persons experienced and with content knowledge
of explosives and risk assessment procedures. The risk management process
should be conducted with persons experienced and with content knowledge of
explosives and familiar with Australian Standards:
AS 2187. Explosives- Storage and use, and
AS/NZS 4360. Risk management
The principles stated in this document are intended as general guidance for the
assistance of underground mining operations using explosives. Underground mining
operations should consider their site circumstances and rely upon their own training
and experience when assessing safety standards and risk management procedures.
This Guidance Note is aimed to promote consistency of best practice in safety and
health in the mining industry. In addition the document provides information and
reference for the identification, assessment and control of hazards associated with
explosives storage, transport and use.
The State of Queensland and its agents will not be held liable for any loss or
damage whatsoever (including liability for negligence and consequential losses)
suffered by any person acting in reliance or purported reliance upon this Guidance
Note.
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Table of Contents
1 PURPOSE AND SCOPE ............................................................................................................................ 5
2 UNDERGROUND MAGAZINES ............................................................................................................. 8
2.1 GENERAL DESIGN REQUIREMENTS............................................................................................ 8 2.1.1 Location .......................................................................................................................................... 8 2.1.2 Ventilation ...................................................................................................................................... 8 2.1.3 Proximity to Ignition Sources ......................................................................................................... 9 2.1.4 Vehicle Access ................................................................................................................................ 9 2.1.5 Ground Conditions ......................................................................................................................... 9 2.1.6 Security ........................................................................................................................................... 9 2.1.7 Markings ....................................................................................................................................... 10 2.1.8 Warning Devices ........................................................................................................................... 11 2.1.9 Segregation ................................................................................................................................... 11 2.1.10 Fire Protection ......................................................................................................................... 11 2.1.11 Earth Terminations .................................................................................................................. 12 2.1.12 Water Installations ................................................................................................................... 12 2.1.13 Electrical Installations ............................................................................................................. 12
2.2 PORTABLE / RELOCATABLE MAGAZINES ............................................................................... 13 2.2.1 Magazine Exteriors ....................................................................................................................... 13 2.2.2 Magazine Interiors........................................................................................................................ 13
2.3 PERMANENT MAGAZINES .......................................................................................................... 13 2.3.1 Backs and Walls ............................................................................................................................ 14 2.3.2 Access ........................................................................................................................................... 14 2.3.3 Elevated Storage ........................................................................................................................... 14
2.4 UNDERGROUND TEMPORARY STORAGE ................................................................................ 14
3 EXPLOSIVES ARRIVAL ON SITE ....................................................................................................... 16
3.1 ARRIVAL POINT OF EXPLOSIVES .............................................................................................. 16 3.2 EXCESS EXPLOSIVES ................................................................................................................... 16
4 TRANSPORT TO THE MAGAZINE .................................................................................................... 17
4.1 TRANSFER UNDERGROUND ....................................................................................................... 17 4.1.1 Transport in a Shaft ...................................................................................................................... 17 4.1.2 Segregation ................................................................................................................................... 17 4.1.3 Security ......................................................................................................................................... 17
5 MANAGEMENT OF THE MAGAZINE ............................................................................................... 18
5.1 STOCK CONTROL .......................................................................................................................... 18 5.1.1 Person in Charge of Magazine ..................................................................................................... 18
5.2 HOUSEKEEPING ............................................................................................................................. 19 5.2.1 Magazine Rules ............................................................................................................................. 19 5.2.2 Prohibited Articles ........................................................................................................................ 20 5.2.3 General Tidiness ........................................................................................................................... 20 5.2.4 Opening Packages ........................................................................................................................ 20 5.2.5 Safety Equipment .......................................................................................................................... 20
5.3 PROCEDURES ................................................................................................................................. 21 5.3.1 Theft or Loss of an Explosive ........................................................................................................ 21 5.3.2 Accountability of Explosives ......................................................................................................... 21 5.3.3 Maintenance ................................................................................................................................. 21 5.3.4 Fire ............................................................................................................................................... 21
6 UNDERGROUND TRANSPORT OF EXPLOSIVES .......................................................................... 22
6.1 GENERAL VEHICLE REQUIREMENTS ....................................................................................... 22 6.2 HIGHER RISK TRANSPORT OF EXPLOSIVES ............................................................................ 22 6.3 SECURITY AND SAFETY WHILE IN TRANSPORT .................................................................... 23 6.4 TRANSPORT BY RAIL ................................................................................................................... 24 6.5 VEHICLE MARKINGS .................................................................................................................... 25 6.6 COMPETENCY OF PERSONS ........................................................................................................ 25 6.7 TRANSPORT ON FOOT .................................................................................................................. 25 6.8 TRANSPORT USING A LOADER BUCKET.................................................................................. 25
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6.9 VEHICLE ACCESS TO EXPLOSIVE STORAGE SECTION ......................................................... 25 6.9.1 Internal Combustion Engines ....................................................................................................... 26 6.9.2 Electric Motors ............................................................................................................................. 26
6.10 MATERIALS HANDLING EQUIPMENT ....................................................................................... 26 6.10.1 Pumps ...................................................................................................................................... 26 6.10.2 Miscellaneous Equipment ........................................................................................................ 27
7 DRILLING BLASTHOLES ..................................................................................................................... 27
8 EXPLOSIVES USE .................................................................................................................................. 28
8.1 RECORDS......................................................................................................................................... 28 8.1.1 Authority to Use Explosives .......................................................................................................... 28 8.1.2 Blast Design .................................................................................................................................. 29 8.1.3 Blast Parameters .......................................................................................................................... 29 8.1.4 Charging Over Shifts .................................................................................................................... 29
8.2 SAFETY PRECAUTIONS ................................................................................................................ 29 8.2.1 Safety Equipment .......................................................................................................................... 29 8.2.2 Handling of Explosives ................................................................................................................. 29 8.2.3 Activities in Proximity ................................................................................................................... 30 8.2.4 Mobile Equipment on Non-electric Blast ...................................................................................... 30 8.2.5 Signage ......................................................................................................................................... 30 8.2.6 Communication Devices ............................................................................................................... 30 8.2.7 Flammable Gas Areas .................................................................................................................. 31
8.3 EXPLOSIVE SELECTION CRITERIA ............................................................................................ 31 8.3.1 Underground Coal Mines ............................................................................................................. 31 8.3.2 Ground Conditions ....................................................................................................................... 32 8.3.3 Blasting in Hot Material ............................................................................................................... 32 8.3.4 Blasting in Oxidizing / Reactive Ground ...................................................................................... 32
8.4 CHARGING OPERATIONS ............................................................................................................ 33 8.4.1 Clearing and Measuring Blastholes ............................................................................................. 33 8.4.2 Priming ......................................................................................................................................... 33 8.4.3 Bulk Explosives ............................................................................................................................. 34 8.4.4 Sleep Time in Blastholes ............................................................................................................... 36
8.5 STEMMING ...................................................................................................................................... 37 8.5.1 Tamping Rods ............................................................................................................................... 37
8.6 INITIATION ..................................................................................................................................... 37 8.6.1 Non-Electric Firing ...................................................................................................................... 38 8.6.2 Electric Firing .............................................................................................................................. 38
9 FIRING ...................................................................................................................................................... 39
9.1 BLAST PERIMETER ....................................................................................................................... 39 9.2 WARNING PROCEDURES ............................................................................................................. 39
9.2.1 External Parties ............................................................................................................................ 39 9.2.2 Withdraw of Personnel ................................................................................................................. 39 9.2.3 Audible Warning Device ............................................................................................................... 40
9.3 RADIO COMMUNICATION ................................................................................................................... 40 9.3.1 Access Guards .............................................................................................................................. 40
9.4 BLASTPED FIRING ......................................................................................................................... 41 9.5 BLAST MONITORING .................................................................................................................... 42
10 POST FIRING ........................................................................................................................................... 43
10.1 EXAMINATION OF SHOT .............................................................................................................. 43 10.2 MISFIRES ......................................................................................................................................... 43
10.2.1 Determination of Misfires ........................................................................................................ 43 10.2.2 Treatment of Misfires ............................................................................................................... 44
11 DISPOSAL OF SURPLUS AND DEFECTIVE EXPLOSIVES ........................................................... 45
11.1 EXPLOSIVES ................................................................................................................................... 45 11.2 EXPLOSIVE PACKAGING ............................................................................................................. 45
12 LIST OF REFERENCED DOCUMENTS .............................................................................................. 46
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2 UNDERGROUND MAGAZINES
2.1 GENERAL DESIGN REQUIREMENTS
2.1.1 Location
When siting an underground magazine the risk management process can be carried
out at the planning and design stage to identify a suitable location. The magazine
should be located an acceptable distance from major service installations so the
possible effects of an explosion will not adversely impact upon winders, electrical
substations, pump stations, ventilation equipment or other important infrastructure
(AS 2187.1). Risk acceptability should be evaluated based on the quantity of
explosives stored in the magazine and the direct distance through rock and along
openings. The more explosives stored the greater the distance needs to be to limit
the consequences of an accidental explosion.
2.1.2 Ventilation
The magazine should ideally be located so that it exhausts directly into a return
airway. This is to ensure that in the event of an explosion fumes travel away from
where persons are working and escape routes. Where a direct connection to a
return airway is not possible then auxiliary ventilation should be used in the
magazine and turned on at all times. Auxiliary ventilation duct access into the
magazine requires adequate security (e.g. fixed bars) to prevent unauthorised
access to the magazine area.
Ventilation flow should be planned to provide for air movement of between 0.3 and
0.7 m/s, and with sufficient quantity to ensure fumes from any diesel engine in the
magazine are diluted to an acceptable concentration. This should ensure that inside
the magazine there is no accumulation of dangerous vapours or a build up of
excessive heat.
Be aware that explosives need to be kept within the prescribed temperature storage
range outlined by the explosives manufacturer. Explosives and initiators are at risk
of burning or exploding at elevated temperatures as initiation sensitivity increases
with temperature. Physical properties (firmness, plasticity, etc) may also change,
and storage life/sleep time may also be reduced, with temperatures changes.
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2.1.3 Proximity to Ignition Sources
When siting the magazine, consideration should be given to its proximity to likely
ignition sources. These could include fuel sources such as refuelling depots,
lubricant bays, oxy-acetylene equipment, rubbish or mineral matter. Location of
magazines in high sulphide areas is to be considered in the risk analysis due to the
hazard of a sulphide dust explosion. The magazine should be located a suitable
distance from blasting conducted in sulphide areas to ensure in the event of an
explosion the flame front does not propagate to the magazine area. An underground
magazine should be a safe distance from accesses and main travel ways.
2.1.4 Vehicle Access
When designing the location of an underground magazine consideration should be
given to hazards that may arise from proximity to vehicular access routes and
roadways used on site. This includes the number of access routes to the magazine
and the types of vehicles and the frequency of their proximity (AS 2187.1).
2.1.5 Ground Conditions
When designing the location of an underground magazine consideration should be
given to the known in-situ ground conditions. Certain explosives can initiate through
impact or friction caused by rock falls or ground control or reinforcements failures.
The magazine should be sited in a region of competent rock to ensure possible
damage caused by rock bolt failure, rock bursts and seismic activity is significantly
reduced. The types of installations of ground support or reinforcement used needs to
be properly engineered to minimise the risks involved.
2.1.6 Security
2.1.6.1 Remote Security
To enhance the security of an underground magazine consideration can be given to
incorporating either a camera or alarm system with the required door and locking
devices specified in this Guidance Note. All alarm, camera fittings and installations
inside the magazine area are required to comply with AS 3000 for electrical
equipment in hazardous locations (refer to Section 1.9.2.2).
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2.1.6.2 Magazine Doors
The security requirements for underground magazines should be in accordance with
AS 2187.1, or a system of at least equivalent safety and security. The doors of the
magazine need to open outwards without causing an obstruction and be fitted with a
restraining device so that accidental closing does not subject the explosives to
jamming, pinching or impact.
2.1.6.3 Locking Devices
Locking devices for all magazine types are required to be in accordance with AS
2187.1, or with a system of at least equivalent security. As specified in AS 2187 the
door or lid of every magazine is required be fitted with a six level ‘safe lock’. Where a
padlock is used it shall have a hardened shackle and pad constructed to provide a
high level of resistance to fracture and rupture. It shall also have a key system
known as a ‘restricted system’ if the padlock is of the pin-tumbler type. Where the
padlock is of the lever type, there shall be a minimum of five levers.
2.1.6.4 Door Hinges
It is important that the integrity of the door hinges and hinge lugs match the integrity
of the lock provided. In the past illegal access to explosives has been gained
through using a hacksaw blade on the hinges of the magazine. To prevent such
access to the hinges the construction of the hinge lugs on the door should be in
accordance with requirements in Australian Standard 2188. The integrity of the weld
used to join the hinge lug to the door is also to be of a satisfactory standard to
prevent the lug from detaching from the magazine, in the event of a forced entry.
The strength of these welds should be monitored at each inspection or audit. Any
non-compliance found during an audit or an inspection should be fixed as soon as
practicable.
2.1.7 Markings
The magazine is to be marked at the entrance with either the word ‘EXPLOSIVE’ or
‘DETONATOR’, as appropriate. In addition an explosive hazard class diamond is
required on the magazine door. A clearly defined ‘NO SMOKING’ or ‘NAKED
FLAMES’ sign should be positioned at the entrance of the magazine to warn
persons entering the magazine.
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Figure 1: Signs to be marked: No Smoking sign, Explosive hazard class diamond, and
Explosives sign.
2.1.8 Warning Devices
Persons should clearly be able to identify the location of an underground magazine.
A flashing light or other warning device should be placed near each magazine.
Employees should easily recognise the warning device used, and the warning
devices should not be apparent when explosives are not present.
2.1.9 Segregation
Storage sites for the explosive magazine and detonator magazine shall be located
as to reduce to acceptable levels the risk of sympathetic detonation between the
different storages. The separation distances specified in AS 2187.1 are based on
international testing and need to be observed as a minimum, however this minimum
distance can be increased to further reduce the risk.
Where separation of detonators and explosives is not possible they need to be
contained a safe distance, in a separate compartment defined by separating walls
that are not in line of sight (AS 2187.1).
2.1.10 Fire Protection
For an underground magazine a fire fighting system that is either remotely or
automatically operated is required. A sprinkler type system should be used where a
diesel-powered vehicle can enter the magazine. It needs to have pipelines and
control valves that are fire resistant and should be of a type recommended by the
manufacturer for the type of explosives used (AS 2187.1). The system should be
clearly identifiable, for example, paint pipes red and clearly mark control valves.
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For a temporary storage area a fire extinguisher should be available in the vicinity of
the magazine. Selection of suitable fire extinguishers and hydrants is dependent on
the hazards present within the magazine area, for example electrical fires, liquid
fires. This should be placed in the fresh airside of the magazine.
2.1.11 Earth Terminations
All exposed metal structures such as pipes, rails and doors that are inside or part of
the magazine should be earthed to control undesirable extraneous electricity.
2.1.12 Water Installations
If water is required within the vicinity of the magazine, the installation needs to be set
up to prevent water coming into contact with the explosives and ensure that the
water does not cause erosion or degradation to the access or foundations of the
magazine. If necessary, provide for drainage and a sump.
2.1.13 Electrical Installations
2.1.13.1 Lighting
Electrical fittings inside the magazine should be avoided, however if no alternative
option is available, wiring should be suitable for electrical equipment in hazardous
areas (AS 3000). Explosion protection for electrical equipment should be provided
according to the classification of the hazardous area. However, the use of electricity
in magazines is referenced in AS 2187 where it states:
“2.1.4 Lighting. Electrical fittings and wiring shall comply with AS 3000 for electrical
equipment in hazardous locations and satisfy the requirements of the Hazardous
Zone Classification”.
Other Australian standards applicable to underground explosive magazines are:
AS 2380, and
AS 2381
A list of explosion-protection techniques and their applicable standards can be found
in ESC-1 ‘Electrical Installations and Equipment in Hazardous Areas at Explosives
Manufacturing Facilities and Storage Areas.’ Alternatively, lighting can be located
outside the magazine and arranged to shine into the magazine.
2.1.13.2 Electrical Equipment
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Electrical equipment and installations, like pumps or explosive mixers should be
avoided if possible, due to the inherent risks associated with their presence.
Electrical arcing of equipment can result in an accidental ignition of explosive or an
explosive atmosphere. If electrical wiring is necessary inside the magazine, all
electrical installations should be suitable for operation in hazardous areas (AS
3000). Professional advice should be sought before installing electrical equipment in
magazine areas.
2.2 PORTABLE / RELOCATABLE MAGAZINES
All portable and relocatable magazines, including converted freight containers, used
underground have to be constructed in accordance with specifications given in AS
2187.1, or with a system of at least equivalent safety and security determined by risk
management process.
2.2.1 Magazine Exteriors
Persons and machinery approaching the magazine need to be able to clearly
distinguish and identify that it is a magazine. Portable and relocatable magazines
should be painted white to improve light reflection and be protected against
corrosion to prevent structural damage (AS 2187.1).
2.2.2 Magazine Interiors
Certain explosives are susceptible to initiation from friction and sparks caused by
metal installations. Where exposed metal is present in the interior of the magazine
an inner lining should be utilised. The inner lining should be free of iron or steel and
be of close jointed construction (AS 2187.1).
2.3 PERMANENT MAGAZINES
Fixed or permanent (non-relocatable) magazines located underground are to be
constructed in accordance with specifications given in AS 2187.1, or with a system
of at least equivalent safety and security determined by risk management process.
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2.3.1 Backs and Walls
The backs and walls of the magazine should be in a condition as to prevent a rock
fall from impacting an explosive. The backs and walls should be free from loose or
protruding rocks or alternatively, meshed and bottled to secure from possible rock
falls. The magazine area should be kept free from water and as necessary be sealed
to prevent water seepage. All intersecting boreholes have to be sealed off and any
butts washed and cleaned to ensure they are free of residual explosives. The interior
and surrounds should be preferably painted white and always kept clean (AS
2187.1).
2.3.2 Access
The access should be inclined or similar to provide adequate drainage to prevent
deterioration of the access roadway and prevent water entering into the magazine.
Vehicles should have to make at least one 90-degree turn to access a magazine to
minimise hazards of an out of control vehicle. For rail access, a suitable derailer or
equivalent should be adjacent to the magazine to prevent entry of a run away
locomotive.
2.3.3 Elevated Storage
Where vehicles have access to the magazine the explosives should be stored in
elevated bays to prevent an out of control vehicle or a reversing vehicle coming into
contact with the explosives. Where detonators are stored in the same magazine as
bulk explosives, a suitable safety distance needs to be provided as well as barriers
or elevated storage bays to prevent access to the detonator area by a powered
vehicle.
2.4 UNDERGROUND TEMPORARY STORAGE
The location of underground temporary storage (working party magazines) should
be carefully and strategically selected using a risk management process that
considers the following potential hazards (this list is not totally inclusive):
To effectively control the temporary storage area it should be located as near
as practicable to where the explosives are to be used.
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To warn others of the presence of explosives the containers in which the
explosives are stored and the surrounding area should be adequately signed.
Where mobile equipment is in the vicinity a warning device such as a flashing
light can be used. Warning devices should not be apparent when explosives
are not present.
The larger the quantity of explosives stored the greater the consequences of
an unplanned ignition. Explosives in the storage area should be kept to a
minimum quantity, preferably not exceeding two days requirements and not
exceeding the quantity needed for the designated operations.
Explosives need to be suitably protected to guard against an unplanned
ignition caused by friction, impact, shock or heat. Containers in which
explosives are stored should be constructed to protect against these hazards
and regularly cleaned of residual explosives.
Detonators in the storage area are stored in locked containers to guard
against theft and adequately segregated from other explosives to reduce the
risk of sympathetic detonation.
Floor of the temporary storage is elevated above roadway level and the
storage level established to prevent water deterioration and so that a runaway
or reversing vehicle is unlikely to contact the explosives.
Plan to ensure that all explosives are removed from the storage area and the
storage area closed when blasting operations for which the explosives were
stored cease.
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3 EXPLOSIVES ARRIVAL ON SITE
3.1 ARRIVAL POINT OF EXPLOSIVES
A risk assessment is to be carried out to identify hazards that may arise with the
arrival of an explosives vehicle onsite. Explosives vehicles should arrive on site in a
location that ensures the magnitude of the hazard and nature of the consequences
are reduced to an acceptable level. Safe allocated stopping areas are required to
reduce the vehicles proximity to populated areas, ignition sources and staff working
areas. The requirements for the transport of explosives by road and rail can be
attained from the Australian Explosives Code 2000.
3.2 EXCESS EXPLOSIVES
The carrier bringing explosives to the site may have explosives onboard that are to
be delivered to other mine sites. These excess explosives represent an additional
hazard and the site senior executive is responsible for the additional risk. Best
practice is for an exact record of all explosives in the consignment to be provided to
the site senior executive before entry to the mine site is authorised.
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4 TRANSPORT TO THE MAGAZINE
4.1 TRANSFER UNDERGROUND
Where possible regularly utilised travel ways such as service shafts or declines
should be avoided for the transfer of explosives from the surface to the underground.
If the only means of access is a decline or service shaft then the explosives should
be transferred at a time as to avoid employees and materials. All employees should
be made aware either through appropriate signage or using a selected radio channel
to broadcast that explosives are to be transferred to the underground storage
section.
4.1.1 Transport in a Shaft
The site senior executive should ensure that there is a standard work instruction
where a mine uses a shaft to lower explosive underground. The following general
precautions should be taken to ensure the safety and security of explosives during
transport in a shaft:
Ensure that the shaft and cage are in sound mechanical condition and repair
Ensure that explosives travel without other equipment and persons.
Ensure that explosives are secured to prevent pinching, impact or friction.
Maintain segregation and transport large quantities of detonators separate to
detonator sensitive explosives.
Ensure that a competent person controls the transit of the explosive
Explosives should be transferred to the shaft and underground storage in an
efficient manner to minimise explosives storage in inappropriate places.
4.1.2 Segregation
Transfer of detonators and explosives underground should be completed separately
as to reduce to acceptable levels the risk of communication of explosion. If
transferred together the materials handling equipment should be suited for the
transport of explosives (refer to Section 5).
4.1.3 Security
The explosives should be promptly transferred to the magazine and not temporarily
stored or delivered to other sections of the mine. The person in charge of the
transfer of the explosives should ensure that explosives are not left unattended or
left on rail carriages or vehicles unless suitably secured.
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5 MANAGEMENT OF THE MAGAZINE
5.1 STOCK CONTROL
5.1.1 Person in Charge of Magazine
A person in charge of the magazine has to demonstrate competency and be
assessed in the storage and handling of explosives before being appointed. The
duties of the person appointed to be in charge of a magazine are given in AS 2187.1
and include the following.
5.1.1.1 Access to Magazine
The person appointed in charge of the magazine is obligated to ensure that only
authorised persons have access to the magazine. The person needs to ensure that
the magazine is secured at all times and the magazine key is in the care of an
authorised person or locked in a secure location (AS 2187.1).
5.1.1.2 Explosive Limits
The person appointed in charge of the magazine has to ensure that the explosives
stock levels in the magazine are within the licensing limits. For determining the
quantity of explosives that can be held within a specific magazine refer to AS
2187.1. Best practice is for a record of the licence to store to be kept at the
magazine location. This will ensure that all authorised personnel with access to the
magazine are aware of the explosive capacity of the magazine.
5.1.1.3 Stacking Packages
The person appointed in charge of the magazine is obligated to check that
packaging for the explosives to be stored in the magazine is of such construction
strength and character that it cannot break or open accidentally. Stacking heights
are not to exceed those recommended by the explosives manufacturer.
If the person in charge of the magazine is not satisfied with the condition of
packaging supplied there is no obligation to store the product in the magazine.
To ensure adequate ventilation, an air gap is to be maintained between the
explosives and the magazine walls and ceilings. (AS 2187.1)
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5.1.1.4 Rotation of Stock
The person appointed in charge of the magazine will ensure that the explosives
stock is rotated on a regular basis and that the explosives are within the expiration
dates indicated by the manufacturer. Explosives that are more than one year old
should not be used without first contacting the explosives manufacturer (source:
Orica Explosives).
5.1.1.5 Record Keeping
The person appointed in charge of the magazine is required to keep a record of
incoming and outgoing stocks. These records need to be kept for a period of not
less than five years (AS 2187.1). The record is to include a balance of all explosives
stored at the magazine. Every attempt has to be made to account for individual
explosive items that are distributed collectively. Best practice is for a second record
of the explosive stock levels to be kept in a separate location. An audit and
inspection of the magazine, its contents and surrounds needs to be conducted and
recorded frequently, preferably monthly and usually not more than every three
months.
5.1.1.6 Record of Underground Storages
The site senior executive needs to ensure an up-to-date record of the number and
location of underground magazines and temporary storage is kept at the mine and
made available to an inspector at the inspector’s request.
5.2 HOUSEKEEPING
5.2.1 Magazine Rules
Magazine rules for the operation of the magazine are to be displayed inside the
magazine in a prominent position (AS 2187.1 – Appendix J). These rules should
include explosives quantities and segregation requirements for correct storage,
security procedures, housekeeping rules and whom to contact for maintenance work
approval.
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5.2.2 Prohibited Articles
Articles that are likely to cause fire or explosion such as cigarettes, matches, radio
transmitters, mobile phones or rubbish of any description shall not be taken into the
magazine (AS 2187.1). A receptacle should be provided at the magazine entrance
for discarding of such items before entering the magazine.
5.2.3 General Tidiness
The floor of the magazine should be kept clean of dirt, empty packaging and
explosives. Floor mats, dustpans and brooms should be provided in the magazine to
clean up. Spillages of explosives should be cleaned up and properly disposed of
immediately (AS 2187.1). It is the responsibility of the magazine keeper to maintain
the magazine in exact condition.
Rubbish bins, waste packaging and other refuge should not be stored inside
magazines.
5.2.4 Opening Packages
Free flowing or friction/impact sensitive explosives should not be opened or left in
the magazine in a condition that could instigate premature ignition. Only suitable
tools appropriate for the opening of explosives shall be used to open packages (AS
2187.1). Explosives such as detonating cord and primers are sensitive and
packages should be open using non-metallic objects.
5.2.5 Safety Equipment
Where appropriate safety equipment should be provided for all persons entering the
magazine. This may include personal protective equipment such as anti-static
footwear, fire retarding clothing, eye protection and gloves. Appropriate personal
protective equipment signs should be displayed at the magazine entrance.
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5.3 PROCEDURES
5.3.1 Theft or Loss of an Explosive
A system or written procedure is required to manage the situation following any
attempted forced entry, theft or unaccountable shortage of an explosive (AS 2187.1).
On detecting a theft or loss of an explosive, the authority holder, who is the persons
licensed to use or store explosives, is required to immediately give the Chief
Inspector of Explosives written notice of the loss (s55 Explosives Act 1999). The site
senior executive then needs to further notify an inspector of mines and the police
(s195 Mining and Quarrying Safety and Health Act 1999 and s198 Coal Mining
Safety and Health Act 1999)
5.3.2 Accountability of Explosives
Sections 79 and 79A of the Mining and Quarrying Safety and Health Regulation
2001 detail the regulatory requirements for dealing with the theft or loss of
explosives and for personal accountabilities.
Every person who has immediate custody or control of any explosives, or a mine,
has an obligation to account for and accurately detail what happens to the explosive
when it leaves that person’s custody or control.
5.3.3 Maintenance
A system or written procedure should be in place to maintain the magazine
installations. Any maintenance work is to be authorised in writing by the person
appointed in charge of the magazine. Where any activity that is likely to generate
heat is to be undertaken inside or on the outside of a magazine the contents of the
magazine are to be emptied and cleaned (AS 2187.1). For hot work, a permit is
required be attained to work, and a fire watch needs to be conducted that extends at
least one hour after the completion of the maintenance.
5.3.4 Fire
An appropriate fire emergency procedure should be in place to deal with fire at or
near the magazine. It should address evacuation of all personnel to a safe location
and securing access to the magazine. The person in charge of the magazine in
conjunction with the mine’s rescue team should develop an emergency procedure.
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In case of a magazine fire, if the explosive is not burning, carefully remove as much
of the explosive as possible. However, if the explosive is burning, evacuate. the
area and do not attempt to fight the fire.
6 UNDERGROUND TRANSPORT OF EXPLOSIVES
6.1 GENERAL VEHICLE REQUIREMENTS
For the safe and secure transport of explosives underground all vehicles should
adhere to the following general requirements:
be in sound mechanical condition and repair.
be powered by diesel fuel.
provide adequate segregation of detonators from other explosives.
all explosives to be transported in a safe and secure manner either in
securely attached containers or other fit for purpose means.
where packaged explosives may be in contact with interior surfaces , the
surfaces should be kept in a clean condition and free from any projections
that are likely to cause damage.
before vehicles are serviced they need to be thoroughly cleaned, and
inspected by a person who has the necessary competence and also be
certified to be free of explosive residues.
6.2 HIGHER RISK TRANSPORT OF EXPLOSIVES
The degree of risk and subsequent requirements for vehicles carrying explosives
underground should be managed based on the types and quantities of explosives
carried and the suitability and condition of the vehicle. Where large quantities of
explosives are transported together there exists the possibility of sympathetic
detonation. For the safe and secure transport of explosives, the vehicles used can
reduce the risk associated with the function by implementing the following controls:
Hazard- Fuel Fire
Use a diesel engine vehicle with diesel fuel that meets AS 3570: Automotive
Diesel Fuel.
Hazard – Electrical fault
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Have electrical wiring protected with conduit and also have a battery isolation
switch located in an accessible position.
Hazard – Exhaust flames/sparks
The vehicle should be fitted with a spark arrestor in accordance with AS 1019.
Hazard – Stray radio current
Electrical detonators should not be transported close to a radio transmitter in
a vehicle unless the radio is turned off or the radio wattage is sufficiently
below the required initiation power. This is to prevent blasting circuit being
energized by the electric field produced by radio transmitters.
Hazard – Vehicle fire
The vehicle should be fitted with a dry-powder fire extinguisher with a rating
not less than 40 B(E), as specified in AS 1850. Alternatively, or in addition, an
automatically operated AFFF (Aqueous Film Forming Foam) system can be
utilised, for a fire under the bonnet. Fire extinguishers are to fight a fire on the
vehicle. However, in the event of the explosive on fire do not attempt to
extinguish the fire, retreat a safe distance from the vehicle.
6.3 SECURITY AND SAFETY WHILE IN TRANSPORT
The following general precautions should be taken to ensure the security and safety
of explosives during transport:
Before leaving the magazine, the vehicle operator needs to ensure that all
explosives are securely stowed and the quantity and type of explosives
recorded.
Explosives should be kept in their original boxes where possible to facilitate
ready identification and containment.
The transport route between the magazine and shot area should be pre-
planned and all relevant mine personnel notified.
No smoking or naked flames allowed within the vicinity of the vehicle. If any
ignition sources are required they should be carried in a sealed container in
an appropriate section of the vehicle.
If the vehicle is unavoidably left unattended (e.g. emergency), it should be
parked in an appropriate area with all receptacles and the vehicle locked.
All vehicles should be parked facing into the walls of the drive to avoid the
hazard of a runaway vehicle.
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6.4 TRANSPORT BY RAIL
The site senior executive needs to ensure that there is a standard work instruction
where rail is used for the transport of explosives underground. The following general
precautions should be taken to ensure the safety and security of explosives during
transport by rail:
Rail cars should have specially designed receptacles to protect sensitive
explosives from pinching, impact and friction.
Segregation between detonators and bulk explosives as well as initiating
systems should be maintained.
Ensure that explosives are not exposed to extraneous electricity from
batteries or overhead trolley wires.
Transport large quantities of explosives on a separate rake from other
material.
Utilise splashguards to ensure that sparks from wheels or brakes cannot
cause ignition.
Figure 2: Charge car with kettles clearly labelled and blue flashing light mounted on drivers
cabin
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6.5 VEHICLE MARKINGS
Vehicles that are used to carry explosives need to be easily identifiable. This
includes being fitted with appropriate signs. Additionally, vehicles carrying explosives
at mine sites are to be easily identified other than by signs, for example a flashing
light of a distinctive colour is required, and this enables, in the underground
environment, to show that explosives are being transported on the vehicle.
Similarly, when vehicles are not carrying explosives the warning signage or light
needs to be inconspicuous, or have signage indicating the vehicle is explosive free.
6.6 COMPETENCY OF PERSONS
Every person required to transport explosives should be authorised. The Mining and
Quarrying Safety and Health Regulation 2001 require that such persons be
authorised in writing by the site senior executive.
6.7 TRANSPORT ON FOOT
Where explosives are transported on foot protective carry containers are to be
provided. These can be fabricated from metal, wood, canvas or other material that
offers some protection to the contents. Ordinary carry bags do not provide adequate
protection to detonators and should not be used. The containers need to be labelled
clearly and segregation of detonators from high explosives maintained.
6.8 TRANSPORT USING A LOADER BUCKET
The transport of explosives using a loader bucket should be limited to bulk
explosives only and when it is not practicable to use any other means. The site
senior executive is required to ensure that there is a standard work instruction for the
transport of explosives using loader buckets. This procedure should include the
following precautions:
A method of securing the explosives and preventing explosives falling out of
the loader bucket.
An outline of the circumstances when a loader bucket may be used for the
transport of explosives.
A method to ensure that no residual explosives remain on the loader after it is
finished transporting.
6.9 VEHICLE ACCESS TO EXPLOSIVE STORAGE SECTION
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Where vehicles have access to the explosives storage section of the magazine (e.g.
forklifts, charge vehicles), they need to have the necessary modifications for
operation within the vicinity of an explosive area. The following requirements are
specified in AS 2187.1 and are applicable to all powered vehicles:
The vehicle shall not be started inside the explosive storage section of the
magazine.
The vehicle shall not be stored in the explosive storage section of the
magazine.
The vehicle shall not be refuelled, maintained or left running unattended
within the vicinity of the magazine.
6.9.1 Internal Combustion Engines
If an internal combustion engine powers the vehicle that accesses the explosive
storage section is required to be equipped with suitable safety modifications for
operation within an explosive area (AS 2187.1). The vehicle should be designed to
protect the explosives against accidental ignition from heat, friction, pressure,
incompatible materials, sparks and extraneous electricity. These hazards can be
controlled as outlined in Sections 5.1 and 5.2 of this Guidance Note.
6.9.2 Electric Motors
Every electric engine that powers a vehicle that accesses the explosive storage
section is required by AS 1915, to be designed to the specifications for electrical
equipment used in explosive atmospheres. This requirement is to protect the
explosives against accidental ignition from heat, friction, pressure, incompatible
materials, sparks and extraneous electricity. These hazards can be controlled as
outlined in Sections 5.1 and 5.2 of this Guidance Note.
6.10 MATERIALS HANDLING EQUIPMENT
6.10.1 Pumps
Where pumps are used for the transfer of bulk explosives there is a potential risk of
an explosion initiated from heat, friction, sparks or electricity. The pump being
fabricated from non-ferrous and non-combustible materials and electrical wiring
being conducted can largely control these hazards. Further guidance for the
requirements of pumps in explosive areas can be attained from AS 2187.1.
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6.10.2 Miscellaneous Equipment
Where miscellaneous equipment such as pallet trucks, trolleys or lifting appliances is
used in the magazine there is a potential risk of an explosion initiated from heat or
sparks. The equipment should be fabricated from non-ferrous and non-combustible
materials and suitable for use within an explosive environment. Further guidance of
miscellaneous equipment in explosive areas can be attained from AS 2187.1.
7 DRILLING BLASTHOLES
The main explosives risks associated with the drilling of blastholes are residual
explosives from previous blast being initiated and poorly drilled holes creating an
unsafe situation during firing. Blast geometry and design is imperative to create safe
discharges and blast results required for mine operating parameters. Blasthole
diameter, angle and length are required to be adequately designed for the selected
drill pattern.. The following standards and procedures should be in place to ensure
holes are drilled safely and create a safe discharge:
The drilling site is prepared and drill holes marked out prior to drilling.
Drilling is not carried out on any face or bench until it has been examined for
misfires and suitably treated (refer to Section 9 of this Guidance Note for the
treatment of misfires).
The driller is provided with a drill design specifying hole and collar lengths,
direction and any expected geotechnical conditions.
The driller records any unusual events during the drilling, for example
cavities, soft rock, or an inability to drill designated holes.
When positioning the drill rig to drill holes along the edge of the bench or
stope the drill rig should be positioned so that the operator has a clear view
of the edge at all times and is protected from falling.
Whilst drilling near the bench or stope edge the drill rig should be orientated
so as to reduce the risk of the drill rig toppling.
Whilst drilling is in progress, explosives being transported or stored in the
area should be kept at a safe distance from the drilling activity.
Drilling is not carried out in a hole where any part of it is considered within an
unacceptable distance from a hole containing explosives.
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Note: If it is essential to drill in, or relatively close to, an old hole or butt, it should be
carried out only with remote-controlled drilling equipment (AS 2187.2). The operator
and all personnel need to be withdrawn a safe distance from the old hole or butt.
8 EXPLOSIVES USE
8.1 RECORDS
8.1.1 Authority to Use Explosives
In the “Foreword” to AS 2187.2 it states “it is a fundamental requirement that
persons are competent and authorized by their employer to handle and use
explosives. Competence, with respect to handling and use of explosives, is
recognized through compliance with relevant legislation and by having
documentation confirming one or both of the following:
1. Current and valid shot firing ticket or licence applicable in the relevant
State or Territory.
2. Currency with relevant competencies or qualification, attained through a
national training package (i.e., endorsed by Australian National Training
Authority or the Department of Education, Science and Training).
Employers of persons who handle and use explosives also have responsibilities with
regard to the safe and secure management of explosives by ensuring that systems
are in place through legislation and their management plan (if required) to provide a
safe place of work. From a security viewpoint, the presence and security of
explosives on a worksite is the ultimate responsibility of the employer.”
8.1.1.1 Mining and Quarrying
Under section 64 of the Mining and Quarrying Safety and Health Regulation 2001, the appointment should be authorised by the site senior executive and recorded in the mine record. Note that a person is considered competent if:
1. That person holds a shotfirers license under the Explosives Act 1999 that is
applicable to the mine’s operations; or
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2. The authorising person is satisfied the person has the competency accepted
by the Advisory Council as qualifying the person to carry out the handling
activity or has satisfactorily completed a competency based training program
for carrying out the handling activity and is competent to carry it out.
8.1.2 Blast Design
Blasts should be planned and designed, by a person qualified or deemed competent
to ensure required blast results. A suitable blast design should be provided to the
shot firer or produced by the shot firer before charging. The blast timing should be
designed to ensure a suitable explosive weight per delay to minimise vibration and
fly and produce the required blast results.
8.1.3 Blast Parameters
Blasting records including all key parameters such as hole specification, burden and
spacing, quantities of explosives used, tie-in pattern and number of delays should be
documented in a manner consistent with AS 2187.2.
8.1.4 Charging Over Shifts
Where charging is conducted over several shifts, there needs to be a written
procedure in place for communication between shifts. This should include
communicating from one shift to another, information about charging and blasted
locations, holes loaded and any unique hazards or unusual circumstances
associated with the shot.
There are many recorded incidents of persons driving both heavy equipment and
other vehicles over unattended charged blastholes, both on surface and
underground. There are many ways to control this hazard, but an exclusion
barricade with signposting is usually effective.
8.2 SAFETY PRECAUTIONS
8.2.1 Safety Equipment
As required safety equipment is to be utilised whilst using explosives. This may
include personal protective equipment such as fire retarding clothing, gloves,
goggles and anti-static footwear.
8.2.2 Handling of Explosives
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Explosives are to be handled in a manner that prevents operations that could lead to
ignition or initiation of explosives. Mishandling of explosives such as throwing of
primers can result in ignition caused by impact with the ground.
8.2.3 Activities in Proximity
There should not be any activity undertaken within the proximity of the shot that
could generate heat or sparks. This includes smoking, naked flames or operation of
machinery (AS 2187.2). Any activity or operation that has the potential to produce
such a hazard could unexpectedly initiate an explosive.
8.2.4 Mobile Equipment on Non-electric Blast
Where mobile equipment is used on non-electric blast there is a premature
explosion hazard or misfire hazard due to running over of detonators. In addition a
premature explosion hazard due to tensile (pulling) failure of signal tube resulting in
“Snap, Slap and Shoot” phenomenon. Mobile vehicle access to the shot should be
via clearly defined access routes and a spotter should be used to control vehicle
movements in areas of restricted visibility.
8.2.5 Signage
Charging areas shall be clearly marked by appropriate warning signs. All possible
approach roads to the shot should be fenced to prevent persons inadvertently
entering the shot. A danger board displaying the words “Danger – Charged Holes”
together with the name and date of the shotfirer or a similar procedure is to be used.
8.2.6 Communication Devices
When using electric initiation, there is a possibility of the blasting circuit being
energized by the electric field produced by radio transmitters. Safe distances for
electric detonators subject to radio frequency radiation can be determined from AS
2187.1, however such devices should never be carried whilst holding or connecting
electric explosives.
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8.2.7 Flammable Gas Areas
Where explosives are used in underground mines where there is a significant
presence of flammable gas, the concentration of the gas should be checked prior to
charging. If the concentration of flammable gas exceeds the stated legislative limit
then charging should not occur. After charging the shot the area should be checked
again to determine whether the shot should be fired. Examinations for the detection
of flammable gas are to be carried out using certified and calibrated gas detectors.
All persons involved in a suspected flammable gas zone need to be made aware of
the hazards associated with varying concentrations of the gas.
8.3 EXPLOSIVE SELECTION CRITERIA
8.3.1 Underground Coal Mines
Explosives used in underground coal mines present a major hazard due to the
presence of methane or coal dust and accidental ignition. Explosives used in
underground coal mines need to be specifically manufactured for this purpose. It is
the responsibility of the site senior executive to ensure that the supplier or
manufacturer is providing explosives that are of the acceptable criteria.
The shotfirer in an underground coal mine needs to ensure the following hazards are
identified and controls put in place:
The concentrations of flammable gas or gases are below the required
legislative requirements.
In areas where the safe concentration of methane is exceeded the shotfirer
should ensure that the time from firing the first detonator to firing the last
detonator is within prescribed tolerance, for example 250 ms.
All exposed coal surfaces within the vicinity of the shot are to be thoroughly
saturated with water or treated with stone dust to ensure an incombustible
coal dust concentration.
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8.3.2 Ground Conditions
When selecting a combination of explosives to be used for the ground conditions
present, the objective is to ensure reliability and safety. Each blasthole that contains
water should be carefully measured and recorded for specific treatment. To avoid
the risk of a misfire wet blastholes should be charged with an explosive with the
appropriate water resistant properties. Before using ANFO in damp blastholes the
effect of water on the explosive column should be considered. If damp blastholes are
required to sleep, an explosive with some water resistant properties is required. A
clear identification system is required to ensure appropriate priming and charging of
wet blastholes, for example spray painting the depth of water next to hole.
8.3.3 Blasting in Hot Material
Hot material is when its temperature is 55C or more, but less than 100C.
Explosives may detonate prematurely if exposed to high temperatures. Temperature
measurements should be taken where hole temperatures are expected to exceed
55C. It is not possible to recommend a safe exposure time for explosives at various
temperatures, because of the wide range of products available and ground
conditions encountered. There needs to be a written procedure for blasting in hot
ground and guidance for this procedure should be sought from the explosives
manufacturer and reference to AS 2187.2.
8.3.4 Blasting in Oxidizing / Reactive Ground
Both sulphide minerals and coal oxidise rapidly when broken and exposed to air. In
operations where such minerals become dispersed as dusts, sparks or heat flash
from blasting can initiate an explosion. The explosives to be used and the charging
practices to be adopted should be developed in consultation with explosive
manufacturers. There needs to be a written procedure for blasting in oxidising or
reactive ground and guidance for this procedure should be sought from the
explosives manufacturer and the following general precautions should be
considered:
Sheathing of ANFO explosives to inhibit exothermic reaction between the
explosives and the material to be blasted.
Wash down all exposed surfaces within the blast vicinity to make fuel
unavailable for a secondary explosion.
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Use adequate stemming in all blastholes to inhibit the development of a
flame front at the collar of a blasthole.
Detonating cord is capable of raising and igniting a dust therefore low
explosive strength detonating cord that is not in contact with rocks or dust
should be used.
Remote firing, preferably from the surface with the mine evacuated.
Selection of the correct stemming for such conditions is most important;
usually a clay-rock stemming is preferred.
8.4 CHARGING OPERATIONS
8.4.1 Clearing and Measuring Blastholes
All blastholes should be checked prior to loading to ensure they are clear and drilled
to the correct depth. Any blocked holes should be cleared with a charging pole or
steel bar. Blastholes should have their depth measured and recorded before
charging.
8.4.2 Priming
Primer cartridges should be handled carefully and the initiating medium used to form
the primer of suitable explosive strength. The primer should be placed in the hole
without using undue force and care taken to avoid the presence of extraneous
matter between cartridges (AS 2187.2). The following general precautions should be
taken when using primers:
Check that none of the explosives are damaged
Any damaged explosives are to be disposed of appropriately and reported to
the shotfirer (refer Section 10).
Ensure that the tails of the initiating medium are neatly placed at the base of
the hole so that they are secure and away from charging vehicles
movements.
If initiating line or primer is lost down the hole the shotfirer should be notified
and the loss recorded and the hole reprimed.
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8.4.3 Bulk Explosives
Care is required in the loading of free-flowing granular explosives and pumpable
explosives to avoid damage to signal tube or allowing them to be pulled into the
hole. The following general precautions should be taken when using bulk explosives:
The shot should be loaded such that the holes furthermost from the access
point are loaded first.
Charging should be done as to prevent damage to the signal tube and
excessive spillage around the hole.
Care should be taken to ensure continuity of the charge.
The rate of delivery needs to be such that overfilling of the hole does not
occur.
Where the truck empties during the charging of a particular hole, the hole
should be suitably identified to ensure that the loading is completed prior to
firing.
8.4.3.1 Pneumatic Charging
Where pneumatic charging devices are used, they shall be effectively earthed. All
charging hose are required to be semi-conductive and have a resistance of not less
than 15000 ohms/m and not more than 2 mega ohms for its total length (AS 2187.2).
Best practice for operation of a pneumatic charging is for antistatic footwear to be
used and for the operator to remove their gloves and earth themselves before
touching any electric detonator.
8.4.3.2 Charge Vehicles
When charging of explosives is conducted using a charge vehicle and basket, the
vehicle needs to have the necessary specifications as outlined in AS 2187.2 and
Section 5 of this Guidance Note. It should be noted that charging off the boom of a
development jumbo is strongly discouraged due to the numerous hazards present in
this practice. The following general precautions should be taken while using purpose
built charge vehicles:
A pre-start check should be conducted to ensure that the vehicle is in sound
condition and repair.
The operator is required to ensure that the tails of the initiating medium are
neatly placed at the base of the hole so that they are secure and away from
the baskets movements (refer to Section 7.2.4 of this Guidance Note).
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Explosive receptacles should be located on the basket so that explosives are
firmly secured. No explosives are to be stored in the articulation region
beneath the boom of charge vehicles if there exists the possibility of
impacting the explosives.
The basket should have suitably designed explosive receptacles to reduce
the risk of an explosive impacting the ground or getting caught in the basket.
All personnel operating the charge car need to be competent to monitor any
support equipment associated with the delivery of the explosives e.g. pump
pressure gauges, emergency stop.
All personnel working in the basket should use a lanyard to reduce the risk of
falling.
Figure 3: Charge car basket with receptacles for explosives
8.4.3.3 Emulsion Loading Vehicles
Where a bulk emulsion vehicle is used to pump the explosive into the borehole, the
vehicle is required to have the necessary specifications as outlined in AS 2187.2 and
Section 5 (Transport of Explosives) of this Guidance Note. The following general
precautions should be taken while using bulk explosives vehicles:
A pre start check should be conducted to ensure that the vehicle is in sound
condition and repair.
All personnel operating the emulsion-loading vehicle need to be competent to
monitor any support equipment associated with the delivery of the explosives,
for example the pump pressure gauges or the emergency stop.
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Vehicle access to the shot should be via clearly defined routes designated by
the shotfirer and a spotter used to control vehicle movements in areas of
restricted visibility (refer to Section 7.2.4 of this Guidance Note).
The mixing and delivery system should be conducted so that the operator
either has full view of explosives deliver point, or has adequate
communication with another operator who does have such a view.
The product should be regularly sampled for quality and density to avoid the
possibility of desensitisation by compression (dead pressing).
When working near the edge of a stope or bench a secure harness system
should be considered to reduce the risk of falling.
Figure 4: Underground emulsion vehicles with control operator and observer.
8.4.4 Sleep Time in Blastholes
Sleep time is defined as the time between charging and firing the shot. The sleep
time of an explosive is important because explosive can often deteriorate under
unfavourable conditions. Conditions such as heat, cold, humidity and water cause
the explosive to deteriorate possibly causing failure of the explosives. Product
deterioration may result in a charge, or part of a charge, failing to explode (misfire).
Best practice is for explosives to be charged and fired at the earliest practicable
time. In large shots load-and-shoot firing eliminates a number of possible processes
of deterioration.
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8.5 STEMMING
Care should be taken to ensure that the down line connected to the primer is not
damaged during the placing of stemming material (AS 2187.2). The following
general precautions should be taken when stemming holes:
A check should be conducted to ensure that the hole has been loaded with
explosives and that the collar height is correct.
The tension on the down lines should be checked to determine whether the
primers are in the product.
Ensure that the stemming material is of a suitable quality and does not
contain large fragments of rock that may cause damage to down lines.
Blastholes charged with gassed bulk explosives should be left unstemmed for
the recommended time to allow for gas bubble expansion.
8.5.1 Tamping Rods
Only wooden or other non-metallic tamping rods are to be used when tamping to
prevent the possibility of an explosion from shock, friction or impact. Care needs to
be taken to ensure that the safety fuse, lead wires, detonating cord or signal tube
connected to the primer are not damaged during the tamping process (AS 2187.2).
Note: A primer should never be tamped due to the risk of explosion caused by
impact.
8.6 INITIATION
The following general procedure should be considered as hazard controls whilst
tying up of shots using non-electric, detonating cord or electric initiated systems:
Initiation tie-in should not commence until all operating equipment has
completed operations in that section of the blast area and the section to be
tied-in has been clearly isolated and defined.
Personnel carrying out the tie-up should either have a tie-up plan or have the
necessary experience to determine the required tie-up.
The tie-up should be conducted in a planned methodical and approved
manner.
After tying up the shot, the tie-up should be checked to confirm that it is
correct. The shotfirer is ultimately responsible for the tie-up and is obligated
to personally check the tie-up before firing.
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8.6.1 Non-Electric Firing
A procedure should be in place that provides a safe system of hook-up of non-
electric explosives. Connections and detonating cord charge weight (grams per
explosive metre) should be in accordance with manufacturers instructions (AS
2187.2).
8.6.2 Electric Firing
Electric detonators are susceptible to accidental initiation by sources of stray
extraneous electricity (AS 2187.2). The following precautions need to be addressed
and maintained:
Keep wire ends, connectors and fittings, shorted (twisted) until immediately
prior to use.
Do not use electric detonators near power lines or other potential sources of
electric current.
If underground the firing is controlled from surface by means of a direct
firing cable and an electrical storm is such as to constitute a danger, work in
connection with charging and firing should cease.
Lightning strikes can cause a potential difference underground that can
cause possible premature detonation. In the event of an electrical storm the
shotfirer is required to assess the immediacy of the storm and decide to fire
or disconnect the control row and clear the blast area.
Keep detonators clear of the ground until charging commences.
Never hold an electronic delay detonator while it is being tested or
programmed.
Do not use plastic liners in blastholes unless they are genuinely and
permanently conductive.
8.6.2.1 Exploders
Only exploders suited to the task should be selected by the shotfirer. Exploders
need to be stored in a clean dry place and the shotfirer is required to ensure that
exploders are maintained in correct working order (AS 2187.2).
8.6.2.2 Circuit Testers
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Before connecting the firing circuit, the detonating circuit and firing circuit shall be
checked to ensure continuity of the circuit. It should be assumed when testing that
an explosion might occur and appropriate precautions are required to clear the
blasting area and choose a safe location for testing. A system should be in place
that ensures that circuit testers are maintained in correct working order (AS 2187.2).
8.6.2.3 Electric Firing Circuits
Where a shot firing cable is used to initiate a blast, the shotfirer should ensure the
cable is adequately protected and insulated for the conditions under which the
blasting is to be carried out. Adequate precautions need to be taken to prevent the
cable from coming into contact with electrical installations, metal object and areas
where possible damage can be caused to the insulating cover.
The cable should be kept short circuited at each end during the charging operation
and at the power end while the leads from the detonators are being connected to
each other or to the firing cables. The short circuit at the power end should not be
opened for connection to the source power until all persons have been withdrawn
from the blasting area. As soon as the blast has been fired the short circuit needs to
be re-established by physical disconnection from the exploder.
9 FIRING
9.1 BLAST PERIMETER
The person responsible for the firing of the shot needs to determine the location or
distance from the shot of the guarded perimeter. This should be determined from a
risk assessment taking into consideration technical concerns or known hazards in
the shot. In some instances it may be required that all personnel are removed to the
surface before firing.
9.2 WARNING PROCEDURES
9.2.1 External Parties
It may necessary to pre-notify certain external parties before conducting blasts. This
may be personnel on the surface, adjoining mines or residences.
9.2.2 Withdraw of Personnel
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Persons in the vicinity of the blasting area and adjacent workings need to be warned
and withdrawn to a safe area before firing the shot. They should not return until the
‘all clear’ signal is given (AS 2187.2). Each person involved in firing the blast has to
be able to reach a predetermined safe position, by walking at normal pace, before
the blasting happens.
9.2.3 Audible Warning Device
Audible warning devices for firing are required for use in underground mines in
continuous secondary blasting situations, as apposed to firing at crib time or end of
shift. Such devices are usually compressed air driven, and in a grizzley and track
haulage situation tied in to warn persons on adjacent levels or sublevels of the
imminent blasting.
9.3 Radio Communication
When underground development blasting can occur during the shift and discrete
isolation of the hazards associated with such firings can be achieved without
evacuation, then effective in-mine communications are essential.
Where a radio channel is used to warn of a firing underground, best practice is to
select a blasting radio channel that is always used. This channel should be the most
commonly used in the particular field locality of the blasting activities. Where there
are likely to be users of other channel in the blast locality, then the firing warning
should be broadcast simultaneously on all those channels.
9.3.1 Access Guards
Adequate roadblocks or warning signs or, where necessary guards shall be placed
along drives to prevent unauthorised machinery or people entering the blast area or
exclusion zone (AS 2187.2). All means of entry to the blasting area need to have
guards to prevent unauthorised access or effective barricades erected across each
place of entry.
The shot should not be fired unless persons have been removed to the ventilation
intake side of the place where firing is to take place and where the resultant fumes
and dust will not affect them.
9.3.1.1 Competency of Guard
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The blast guard is required to understand where their location is and the sequence
of events that will take place while the shot is being fired. They should park their
vehicle at 90 degrees to the flow of traffic and have suitable markings. If someone
does drive past the blast area they shall notify the shotfirer immediately so that the
blast is stopped.
9.3.1.2 Guard Location Sheet
Where there are numerous guards required, say three or more, best practice is for a
guard location and radio procedure record to be kept with persons who perform the
duty of blast guard and the shotfirer. This document can include such things as blast
guard’s names and responsibilities. A pre-firing security check is then to be
undertaken by the shotfirer using the radio and a map of the blast area to confirm
the guard’s locations. This alleviates the possibility of a blast guard not being
involved in the final check by the shot firer prior to firing.
9.4 BLASTPED FIRING
The underground BlastPED uses the PED Transmission System to communicate
with remotely installed receiver/exploders to remotely initiate electric detonators or
starters. Where a BlastPED is used for remote firing the firing cable should be
shorted (twisted) together until ready to connect up to the terminals of the receiver.
The user connecting the cable should ensure that the BlastPED is not synchronised
or the key turned to the firing position until immediately prior to firing. It is then up to
the PED call operator to enter the ‘arm and blast' command from security disk and
transmit the messages, once the area has been cleared of personnel and
permission received to fire.
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Figure 5: Underground remote blasting using BlastPED system.
9.5 BLAST MONITORING
Where blasting is conducted in close proximity to buildings or structures, ground
vibration and airblast overpressure needs to be monitored to record the blast
characteristics and in the longer term provide help to ensure that the probability of
damage or human discomfort is kept to a minimum. Where vibration is of concern
the explosive weight per delay should be limited. Where protection from fly is
necessary, precautions such as the use of blasting mats or other suitable cover and
limiting the explosive weight per delay can be used.
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10 POST FIRING
10.1 EXAMINATION OF SHOT
The shot firer is responsible for examining the site to ensure that no unfired
explosives remains and that it is suitable for work to commence again. Before
examining the shot, consideration should be given to the noxious fumes present and
integrity of surrounding areas (AS 2187.1). Fumes and toxic gases arising from the
explosion should have been effectively dispersed before re-entry of any persons.
Senses of sight and smell should be sufficient for most determination, but oxygen
deficiency is a real risk and caution is advised in small headings. In these instances
the mine atmosphere should be sampled. If no misfires are evident, the ‘all clear’
signal can be given and the blast guards dismissed.
10.2 MISFIRES
A written procedure or standard work instruction is required that provides a safe
system of entry and inspection for misfires and their treatment. This is to include the
method used for the detection of a misfire. The precautionary interval allowed before
the shotfirer can conduct an examination of the site and the recording and treatment
of misfires. A written record of the location and details of the misfired shot is to be
kept. By definition in the Explosives Act 1999 an “explosive incident” is an event,
including a misfire, with the potential to cause death or injury to a persons or
unexpected damage to property and as such is required to be reported to the Chief
Inspector of Explosives
10.2.1 Determination of Misfires
Every hole that has been charged with explosives is considered a misfire until
proven otherwise. Methods used to determine if a misfire has occurred are based on
many factors, including appropriate training, standard work instructions and
guidance from AS 2187.2. There are certain events that indicate a misfire has
occurred, these include:
(a) If using safety fuse, the number of shots counted is less than the number of
holes fired or a disagreement on the count of shots fired.
(b) If damaged safety fuse, detonating cord, lead wires or unfired signal tube is
exposed in a hole that has been fired.
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(c) Evidence of cutoffs, butts or remaining portions of holes (e.g. boulders with
drill holes) that are suspected of containing explosives has been shown to be
free of explosives.
(d) Holes that have slumped between charging and firing due to dispersion of
the explosive from water ingress or through joints and fissures.
(e) If during the normal excavation of the blasted ground, uninitiated or residual
explosives are found or the load out machine encounters poor ‘diggability’ of
the blasted ground.
The shotfirer should conduct a careful examination amongst the debris for
explosives, which if present shall be removed to a safe place and disposed of in
accordance with Section 10.1 of this Guidance Note.
10.2.2 Treatment of Misfires
The method used to treat a misfire should be based on risk assessment and a
combination of other factors, including appropriate training, standard work
instructions and information in AS 2187.2. The following methods can be utilised for
the treatment of potential and determined misfires:
(a) To remove the hazard of residual explosives and blasting gases trapped within
the blast it is best practice to use water sprinklers on the shot area immediately
after firing.
(b) Stemming may be removed by applying water under pressure, compressed air,
or a mixture of water and compressed air through a non-ferous blowpipe. After
removal a fresh primer can be inserted and the blasthole stemmed and fired.
Note: The use of compressed air alone is not encouraged. Where it is used,
special precautions should be taken to minimise the dangers from static
electricity and impact (AS 2187.2)
(c) If the down lines are considered to be in good condition, an attempt may be
made to refire. Drilling a relieving hole parallel to the original blasthole and
charging and firing.
(d) Drilling a relieving hole parallel to the original blasthole and charging and firing.
(e) If a misfire is suspected at any time during mining operations, the operations
have to cease and a detailed inspection conducted by a shotfirer, or competent
person, should commence.
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11 DISPOSAL OF SURPLUS AND DEFECTIVE EXPLOSIVES
11.1 EXPLOSIVES
Explosives that are considered unsafe to transport or for storage are required to be
destroyed in a safe manner in compliance with AS2187.1 – Section 8. Explosives
are not to be thrown away, buried or placed with garbage but treated in the following
approach:
(a) Explosives other than detonators can be disposed of by burning, detonating
(providing a fresh charge is used and no detonators are inserted into
deteriorated explosives) and by dissolving in water.
(b) Detonators and detonating relays may be disposed of by either detonation or
burning in a furnace specially constructed and approved for the purpose.
11.2 EXPLOSIVE PACKAGING
Best Practice for the disposal of explosives is for a system to be in place so that
empty explosive packaging is double checked by independent people before
disposal. In instances where explosive packaging is to be used for other applications
the labels should be clearly marked as to not create uncertainty of the packagings
contents. Disposing of the explosives in a separate container from normal waste will
ensure that discrepancies resulting from accidental disposal can possibly be traced.
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12 LIST OF REFERENCED DOCUMENTS
Australian Standards
AS 1019 Internal combustion engines – Spark emission control devices
AS 1850 Portable fire extinguishers – Classification, rating and performance
testing
AS 1915 Electrical equipment for explosive atmospheres – Battery-operated
vehicles
AS 2187.0 Explosives – Storage, transport and use Part 0: Terminology
AS 2187.1 Explosives – Storage, transport and use Part 1: Storage
AS 2187.2 Explosives – Storage and use Part 2: Use of explosives
AS 2188 Relocatable magazines for storage
AS 2380.1 Electrical equipment for explosive atmospheres – Explosive protection
techniques – General requirements
AS 2381 Classification of hazardous areas – Explosive gas atmospheres
AS 3000 Electrical Installations
AS 3570 Automotive Diesel Fuel
HB13 Electrical equipment in hazardous areas - Handbook
AS 4360 A basic introduction to managing risk
Other Publications
1) Australian Explosives Code 2000 – Australian Code for the Transport of
Explosives by Road and Rail
2) ESC-1 Electrical Installations and Equipment in Hazardous Areas at
Explosives Manufacturing Facilities and Storage Areas
***
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